Use SPACE_RenderBox if available, as SPACE_AreaBox is "dangerous".
Make the SPACE_RenderBox compatibility functions public
Use SPACE_RenderBox compatibility function in tree code
Update theme.c to use SPACE_RenderBox compatiblity function
Update history_local.c to use SPACE_RenderBox compatibility function
Only include rsvg-cairo.h if it isn't already
Error in RISC OS form entry API changes.

When the form entry changes were made the RISC OS implementation was
updated but the loop that counts entries was using an incorrect loop
iterator variable which was never incremented hence causing an
infinite loop.
Remove unecessary form debug

Additionaly we make the curl fetcher report errors instead of
uninitialised buffer.